Source : Webster's Revised Unabridged Dictionary (1913)

Mischievous \Mis"chie*vous\, a.
   Causing mischief; harmful; hurtful; -- now often applied
   where the evil is done carelessly or in sport; as, a
   mischievous child. ``Most mischievous foul sin.'' --Shak.

         This false, wily, doubling disposition is intolerably
         mischievous to society.                  --South.

   Syn: Harmful; hurtful; detrimental; noxious; pernicious;
        destructive. -- {Mis"chie*vous*ly}, adv. --
        {Mis"chie*vous*ness}, n.

Source : WordNet®

mischievous
     adj 1: naughtily or annoyingly playful; "teasing and worrying with
            impish laughter" [syn: {impish}, {implike}, {pixilated},
             {prankish}, {puckish}]
     2: badly behaved; "he was saucy and mischievous in school"; "a
        naughty boy" [syn: {naughty}]
     3: deliberately causing harm or damage; "mischievous rumors and
        falsehoods"